Soldering method is widely known as a method of mounting an electronic component on a substrate. When the electronic component to be mounted is a small part to be used in a portable appliance, if a sufficient soldering area is not available and the solder amount is small in the junction, it is attempted to reinforce the solder junction by a resin adhesive. Or if the strength of soldering material is low and it is hard to assure enough junction strength, the solder junction is often reinforced by resin adhesive. Such technology is disclosed, for example, in Japanese Patent Application Laid-Open No. 2004-146433.
However, such mounting reinforcing method of solder junction by resin adhesive has the following problems. First, this method additionally requires an extra step of applying resin by dispenser or the like for supplying the resin adhesive to the substrate or electronic component, and the manufacturing process is complicated and the manufacturing cost is increased. At the same time, if the electronic component is small, it is hard to assure necessary space for supplying the resin adhesive. Or if the resin adhesive is applied around the electronic component after it is mounted, it is hard to form a resin reinforced part having enough reinforcing effect by invading the resin adhesive into a small gap of electronic component and substrate in the case of a small part, and the junction reliability after mounting is not assured.